In the conventional cassette tape player for cars using magnetic tapes, no vibration isolation mechanism has been substantially provided although the performance of the player falls due to wow and flutter caused by the vibration of the car, because the degradation of the performance is not reagarded as very serious problem.
However, when an optical disk player for scanning and reproducing high-density signals recorded on a disk by the use of an optical pickup is mounted in the moving object, such as the automobile, the aircraft or the like, sound omissions tend to occur due to vibrations of the moving object. Therefore, the principal part of the player is placed on a player frame through rubber cushions so as to be insulated from the vibration. But quality factor Q of the resonance region of the vibration generated in the principal part of the player tends to be inevitably large, so that it is often difficult to have the player operated normally. In addition, the frequency band of the vibrations caused under various severe conditions with which the car is met, normally includes the above resonance region.
Therefore, if the optical disk player for cars is isolated from the vibrations only by rubber cushions, sound omissions occur, and it becomes difficult to enable the optical disk player to be normally operated.
Hence, the following mechanism is proposed as the vibration isolation mechanism of the optical disk player for cars instead of rubber cushions. In the mechanism, a movable chassis (on which an optical pick-up, a turntable and the like are mounted) is suspended by suspension coiled springs in several positions of a frame such as a stationary chassis or a cabinet, and dampers which prevent the movable chassis from vibrating are inserted between the frame and the movable chassis so that the movable chassis can be floated with respect to the frame. Thus, resonance frequency f.sub.O in the lateral (horizontal) direction of the vibration system is decreased. Hence, by adoption of the above vibration isolation mechanisum, the slope of Q-value of the resonance region becomes moderate enough at the leading edge of the slope in comparison with the case in which the rubber cushion is adopted, so that the noted sound omission does not occur, and the vibration isolation characteristic is greatly improved.
However, if the optical disk player having the vibration isolation mechanism as described above is mounted on the car, the following further trouble arises.
When the frame is mounted in the player mounting position of the car at a given angle with the horizontal plane of the car, the direction of the gravity acting on the movable chassis changes, so that the movable chassis tends to be displaced from a neutral equilibrium position with respect to the frame.
The movable chassis is displaced from the neutral equilibrium position with respect to the frame until the dampers are elastically deformed to re-establish an equilibrium state. Thereby, the vibration isolation characteristic of the damper is degraded. In addition, as the movable chassis deviates from the neutral equilibrium position with respect to the frame, the distance between the movable chassis and the frame in the displacement direction of the movable chassis is decreased, so that the movable range in the displacement direction of the movable chassis is decreased with respect to the frame.